1. Field of the Invention
The present invention relates to a plasma display device, and more particularly, to a passive apparatus that manipulates the flow of heated air within a plasma display device preventing parts of the display panel and any air from reaching an extremely high temperature during the functioning of the plasma display device.
2. Description of the Related Art
It is well known that heat is generated in a plasma display panel (PDP) of a plasma display device during the functioning of the PDP. Especially in today's more modern PDP's, the amount of gas discharge may be increased in the PDP to improve brightness, thereby producing even more heat. As components within a plasma display device heat up, the surrounding air is heated. The heated air then rises in the space between the display and the circuit components to the top of the plasma display device where it then emerges out from the top of the plasma display device.
Therefore, in plasma display devices, the PDP is mounted to a chassis base that is formed of a material having good heat conductibility, and a heat-spreading sheet (or thermal conduction sheet) is interposed between the PDP and the chassis base. The heat generated in such a PDP is transmitted through the heat-spreading sheet and chassis base to outside the device. The chassis base is made of a metal such as aluminum and is produced using a die casting process, and the heat-spreading sheet is made of a silicone-based resin.
In addition to the heat generated in the PDP, heat is also produced in various drive circuits (e.g., an X,Y board, an image processing board, a switching mode power supply, etc.), which are mounted to one side of the chassis base. Therefore, in order to ensure a high quality device, it is necessary to prevent an increase in the internal temperature of the plasma display device by the heat generated as a result of the drive circuits.
Different configurations have been disclosed with such a purpose. For example, in Japanese Laid-Open Patent No. 2001-83888, a heat transmission element realized through a heat pipe or heat sink is used to cool the plasma display device. Also, in Japanese Laid-Open Patent No. 2001-282114, differences in temperature between a display section and a non-display section of a PDP, or between the non-display section and external electrodes are reduced using heat pipes.
However, with the use of separate elements such as heat pipes and heat sinks to dissipate the heat in the plasma display device, although some degree of cooling can be expected through such elements, heat generated at specific areas of the plasma display device can reach excessively high temperatures. The flow of hot air rises from the area of heat generation as a result of natural convection current characteristics, and in most plasma display devices including those described above, the hot air that has traveled upward from the area of heat generation simply exits the device. This may pose safety risks to users considering that the drive circuits (e.g., the switching mode power supply board or SMPS board) operate at temperatures of up to 90° C. Unless the air heated by such circuit elements is cooled or dispersed before exiting from the plasma display device, the hot air emerging from such components can harm a user that should happen to touch the plasma display panel or should happen to place the user's hands in the vicinity of where the hottest air exits from the inside of the plasma display device. In other words, if the convective air currents within a functioning plasma display device are not managed properly, certain portions on the upper edge of the plasma display device and air emerging from these certain portions on the upper edge of the plasma display device can reach excessively high temperatures and thus cause a safety hazard to users who may come into close contact with the plasma display device. Especially immediately above a high heat generating component such as the switching mode power supply, the air rising and exiting the plasma display device can be extremely hot. However, at the same time, portions along the upper edge of the plasma display device that are not situated directly above heat producing components can be very cool. Thus, along the top edge of the plasma display device, there are cool portions and very hot portions, depending on what circuit components lie directly below. In addition, the air emerging from the top edge of the plasma display device varies in temperature along the top edge. There are parts of the top edge where very hot air emerges and other portions along the top edge where relatively cool air emerges. This temperature disparity along the top edge of the plasma display device, especially when certain portions of the top edge are dangerously hot, needs to be moderated.
Therefore, there is a need to effectively, safely and efficiently control the air flow inside the plasma display device so that pockets and currents of extremely hot air do not exit the device and pose a threat to users. Also, there is a need to control the convective air currents within a functioning plasma display device so that portions along an upper edge of the plasma display panel to not reach excessively high temperatures and pose a safety threat to users of the plasma display device.